I stayed 5 nights at Karolyn Court, a serviced apartment. Bang in the centre of Bangkok CBD, 2 blocks from the main road.
More than exceeded my expectations. Pool, gym, secure, clean, quiet, aircon in bedrooms and living area, fridge/freezer, gas stove, microwave, balcony, next to MRT, flexible checkout time, wonderful and helpful english-speaking staff. I cannot recommend this place enough.